tailieunhanh - Ecological Risk Assessment for Contaminated Sites - Chapter 3

Phân tích sự tiếp xúc Các phần đầu tiên của vụ án sẽ đối phó với bằng chứng của nguyên đơn mà có xu hướng để hiển thị hoặc [sic] được thiết kế để hiển thị . rằng các vật liệu độc hại được trên các vùng đất của các bị cáo, mà nó di cư, mà nó đã vào trong nước trong số lượng đủ để tạo thành một mối nguy hiểm tiềm năng . Khi bằng chứng về những vấn đề được trình bày. . bạn sẽ được yêu cầu đưa ra quyết định là nguyên đơn đã thiết. | 3 Analysis of Exposure The first part of the case will deal with the plaintiff s evidence which tends to show or sic designed to show . that the toxic materials were on the lands of the defendants that it migrated that it got into the water in sufficient quantity to constitute a potential hazard . When the evidence on these issues is presented . you will be asked to make a decision as to whether the plaintiff has established all of these elements by a preponderance of evidence. If the answer is negative that is the end of the case. Judge D. J. Skinner 1986 instructions to the jury in the Woburn MA civil action Exposure is the contact or co-occurrence of a contaminant with a receptor. The analysis of exposure estimates the magnitude of exposure of the endpoint entities to contaminants distributed in space and time. For contaminated sites it is necessary to consider the exposures due to current conditions and future conditions. Under current conditions the endpoint organisms are exposed to the contaminants that have been determined through chemical or radiochemical analysis to occur in surface water sediments soil shallow groundwater air and food items. This is referred to as the current baseline exposure. One future condition that must be considered is the future baseline. This is the exposure that will occur if no remedial actions are taken to isolate remove or destroy the contaminants. In general the future baseline is assumed to be the same as or not worse than the current baseline so it need not be estimated. However if exposures may increase in the future resulting in increased risks a separate estimate of future exposure must be generated. The most common reason for exposures to increase is that contaminants are migrating out of the source leading to increasing concentrations or extent of contamination. Another reason which is seldom considered is that succession will occur on the site resulting in improved habitat quality more species exposed and more .